EVERETT, Wash. — With just three years left on a hard deadline to prove its fusion approach works, Helion Energy is still wrestling with fundamental questions — and it’s building a new, smaller machine to help find answers faster.
Since launching more than a decade ago, Helion has built increasingly larger prototype devices to test and refine its fusion technology as it races to deliver a source of nearly limitless clean energy. But by 2028, Helion is contractually obligated to have a commercial facility producing energy from fusion reactions, essentially replicating the physics that power the sun.
So now it’s going small.
The company is building a downsized testbed device called “Tiny Merge,” a machine less than one-eighth the size of Polaris, its seventh-generation and final prototype. The decision reflects the reality that key issues remain that Helion’s larger, more expensive prototypes haven’t fully resolved. These concerns must be addressed before final designs for a power plant can be locked in.
“With this agile testbed, we will be able to test new ideas with much less energy and far fewer resource requirements, meaning we can iterate faster than we can on full-scale machines such as Polaris,” said Michael Hua, Helion’s senior director of radiation safety and nuclear science.
GeekWire got a sneak peek at Tiny Merge during a recent tour of the company’s sprawling R&D facility north of Seattle. Behind massive curtains in a cordoned-off section of the building sits the gleaming, tubular fusion device measuring roughly 8 feet long.
Running parallel to the machine are two rows of tall shelving — heavy-duty versions of what you’d find at a home improvement store — that will eventually hold hundreds of mini-fridge-sized capacitors to store power flowing into and out of the device. Helion plans to have Tiny Merge up and running by the end of the summer, leaving roughly two years to incorporate what it learns into final designs.
The stakes couldn’t be higher. Over in Eastern Washington, Helion has broken ground on Orion, a facility that it hopes will be the first to produce fusion energy at a commercial scale. It’s a feat no one has yet accomplished, though more than 45 companies are trying.
Helion has made the sector’s most aggressive timeline commitment through a deal with Microsoft to supply electricity from Orion for a data center development starting in 2028. Miss that deadline, and Helion faces financial penalties from Microsoft and partner Constellation.
The company is counting on Tiny Merge to help make that big bet pay off.
Fusion works by heating matter and compressing it into a plasma, a superheated state in which atoms are stripped of their electrons. In those extreme conditions, atomic nuclei collide, fuse and release energy. The process holds enormous promise for abundant clean power, but achieving it at scale remains a formidable scientific challenge.
The team’s first tests with Tiny Merge will focus on the formation and merging of plasma rings, said Manav Singh, Helion’s director of electrical engineering. The company has researched this with previous prototypes, Singh said, but new results have prompted further questions. “There’s a few much more deep investigations we want to do,” he added.
Helion and the broader fusion industry have made measurable progress in recent years, with devices hitting new records in temperature and pressure. Companies have poured significant funding into the pursuit, with Helion alone raising more than $1 billion from investors including OpenAI CEO Sam Altman.
But plenty of skeptics remain, arguing that grid-scale fusion energy is still many years away — if it ever arrives.
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